Sensing edges for doors are, per se, generally well known. Such sensing edges generally include an elongate outer sheath in which a force sensing switch is positioned. Upon the application of force to the sheath, the force sensing switch actuates suitable control circuitry for controlling the movement of the door. The force sensing switch positioned within the sheath typically comprises a pair of flexible, electrically conductive sheets positioned on the upper and lower sides of a layer of nonconducting foam having a plurality of openings extending therethrough from the upper to the lower side. Upon application of force to the sheath, either or both of the conductive sheets are deflected into electrically conductive engagement with each other, to thereby actuate suitable control circuitry for controlling the door.
Conventional sensing edges, including the above described switch, are not as versatile or as responsive as that contemplated in the present invention. For instance, the typical sensing edge includes conductors attached to the sensor for transmitting the sensing signal to appropriate control circuitry. The conductors exit the sheath of the sensing edge usually through an aperture that is located either on the side surface of the sheath or on the top edge of the sheath. In addition, the aperture is placed at a point that is within the range of the sensor's ability to sense forces. This arrangement limits the use of the sensing edge in two ways.
First, because the conductors exit the sheath at a point within the sensing range, the sensor is not able to detect forces which are proximate to that area. In other words, the conductors inhibit the normal operation of the sensor and thus the sensor may be unable to fully function in the spot that the wires exit the sheath. This is important because often objects move into the area bounded by a side surface of the door and it is important that the sensing edge be able to function at that location.
Second, since many of the doors to which the sensing edge may be attached are movably mounted on a track, the placement of the conductors through the sheath at a point located outside of the track area is cumbersome to the installer. The wires must be tucked away so that the operation of the door along the track is not inhibited.
Another common problem with conventional sensing edges is their difficulty of installation. Since the conductors exit the sheath through an aperture that is located either on the end surface of the sheath or on the top edge of the sheath, the installer of the sensing edge must determine before installation whether he is working with circuitry that is going to be placed on the right hand side of the door, or on the left hand side. If the installer goes out to the job site and in the middle of an installation discovers that for some reason the control circuitry must be located on a different side of the door than was originally planned, he must then take the sensing edge that is currently in his possession and exchange it for another sensing edge which has the conductors placed on the other side. The reason for this is that since conductors exit the sheath from the end, the sensing edge is either a right-handed or left-handed edge. Where the sensor conductors exit the sheath from the top, they do so at a point which makes the edge unusable at that point, as described above. Also, placement of the conductors through the top of the sheath has proven troublesome since the conductors interfere with the proper operation of the door along the track.
The present invention is directed to a sensing edge for a door for sensing objects that come into contact with the sensing edge during door closing. The sensing edge in the present invention overcomes the problems inherent in the prior art in two ways. First, the present sensing edge has an increased sensing area due to the placement of the conductors through an end surface of the sheath. Second, two apertures are located in the hood of the sheath so that the installer of the sensing edge can place the conductors through either one of the apertures. This results in increased versatility since the side of the sensing edge with the aperture with the conductors extending therethrough can be positioned proximate either side surface of the door thereby making the sensing edge bilateral.